12. Derinkuyu: The Ancient Turkish City built to house 20,000 people- Underground.
The Cappadocia region of Turkey is home to several unique, underground cities. The largest of them is the multi-leveled city of Derinkuyu, found in the Nevşehir Province. Derinkuyu was an engineering feat, built on multiple levels extending to 85 meters below ground. Each level was painstakingly excavated by hand without the use of machinery to create a subterranean refuge that could accommodate at least 20,000 people.
The city’s heyday occurred between 780-1180 AD when local Christians used it as a refuge during the Arab-Byzantine wars. The city’s great stone doors would have sealed the refugees safely inside so they could wait out the danger of the outside world in a working town perfectly equipped for an extended stay. The city was supplied with air and water by a 55meter ventilation shaft and interior wells. The human-made caves could accommodate humans and animals as well as storerooms for food and workshops for olive oil and wine. There was even a school and on the lowest level excavated so far a cruciform church.
Derinkuyo continued in use until 1923 when Cappadocia’s Christian population was relocated to Greece. However, while experts know a great deal about Derinkuyo’s general usage over the centuries, they do not understand why it was initially constructed. The excavation of the underground city was begun by the Phrygian race, some belief as early as the 8thcentury BC. However, nobody knows their motivation for beginning Derinkuyu.